<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <!-- <meta name="viewport" content="width=device-width, initial-scale=1.0"> -->
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
    <title>Document</title>
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    <link rel="stylesheet" href="http://at.alicdn.com/t/font_1750921_l2izytb8e8m.css">
    <script>
        (function flexible (window, document) {
  var docEl = document.documentElement
  var dpr = window.devicePixelRatio || 1

  // adjust body font size
  function setBodyFontSize () {
    if (document.body) {
      document.body.style.fontSize = (12 * dpr) + 'px'
    }
    else {
      document.addEventListener('DOMContentLoaded', setBodyFontSize)
    }
  }
  setBodyFontSize();

  // set 1rem = viewWidth / 10
  function setRemUnit () {
    var rem = docEl.clientWidth / 10
    docEl.style.fontSize = rem + 'px'
  }

  setRemUnit()

  // reset rem unit on page resize
  window.addEventListener('resize', setRemUnit)
  window.addEventListener('pageshow', function (e) {
    if (e.persisted) {
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  // detect 0.5px supports
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    var fakeBody = document.createElement('body')
    var testElement = document.createElement('div')
    testElement.style.border = '.5px solid transparent'
    fakeBody.appendChild(testElement)
    docEl.appendChild(fakeBody)
    if (testElement.offsetHeight === 1) {
      docEl.classList.add('hairlines')
    }
    docEl.removeChild(fakeBody)
  }
}(window, document))
    </script>
    <style>
        html {
            font-size: 20px;
        }

        .btn {
            width: 6rem;
            height: 3rem;
            line-height: 3rem;
            font-size: 1.2rem;
            display: inline-block;
            background: #06c;
            color: #fff;
            border-radius: .5rem;
            text-decoration: none;
            text-align: center;
        }
    </style>
</head>

<body>
    <div>hello</div>
    <i class="icon iconfont icon-xinxi">ss</i>
    <i class="icon iconfont icon-bianminshenghuo">ss</i>
    <div class="btn">Button</div>
</body>

</html>